Temperature responsive smart textile

ABSTRACT

A textile fabric has at least one raised surface incorporating multicomponent fibers formed of at least a first polymer and a second polymer disposed in side-by-side relationship. The first polymer and the second polymer exhibit differential thermal elongation, which causes the multicomponent fibers to bend or curl and reversibly recover in response to changes in temperature, thereby adjusting insulation performance of the textile fabric in response to ambient conditions.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. application Ser. No.11/835,632, filed Aug. 8, 2007, now U.S. Pat. No. 8,192,824, whichclaims benefit from U.S. Provisional Patent Application 60/940,775,filed May 30, 2007, and U.S. Provisional Patent Application 60/840,813,filed Aug. 29, 2006. The entire disclosures of all of the aforementionedapplications are incorporated herein by reference.

This invention was made with government support under ContractW91CRB-09-C-0059 awarded by US Army RDECOM CONTR CRT. The government hascertain rights in the invention.

TECHNICAL FIELD

This invention relates to textile fabrics, and more particularly totextile fabrics responsive to changes in ambient temperature.

BACKGROUND

Standard textile fabrics have properties set during fabric constructionthat are maintained despite changes in ambient conditions and/orphysical activity. These standard products are quite effective,especially when layered with other textile fabrics for synergisticeffect and enhancement of comfort.

SUMMARY

Textile fabrics with raised surfaces, like fleece, either single face ordouble face, have different pile heights and different density fordifferent ambient conditions and different activity.

According to one aspect, a textile fabric has at least one raisedsurface incorporating yarn comprising multicomponent fibers (e.g.,bi-component fibers, tri-component fibers, etc.) formed of at least afirst polymer and a second polymer disposed in side-by-siderelationship. The first polymer and the second polymer exhibitdifferential thermal elongation (e.g., expansion and/or contraction),which causes the multicomponent fibers to bend or curl and reversiblyrecover in response to changes in temperature, thereby adjustinginsulation performance of the textile fabric in response to ambientconditions.

Preferred implementations may include one or more of the followingadditional features. At least one of the first polymer and the secondpolymer is a thermoplastic polymer with low glass transitiontemperature. The first polymer is a polypropylene and the second polymeris a polyethylene (e.g., linear low density polyethylene). The firstpolymer is a first polypropylene (e.g., an isotactic polypropylene) andthe second polymer is a second polypropylene (e.g., a syndiotacticpolypropylene) different from the first polypropylene. Themulticomponent fibers may also include a third polypropylene differentfrom both the first polypropylene and the second polypropylene. The yarnhas a denier of about 90 to about 500, e.g., about 150 to about 360,e.g., about 160. The yarn has a tenacity of about 0.5 grams-force perdenier to about 5.0 grams-force per denier, e.g., 0.9 grams-force perdenier to about 2.4 grams-force per denier, e.g., about 2.3 grams-forceper denier. The yarn has a filament count of 36 to 144. In some cases,for example, the yarn is a 72 filament yarn. The multicomponent fibersmay have a round cross-section and the first polymer and the secondpolymer are arranged in a side-by-side configuration. The multicomponentfibers have a trilobal cross-section. The multicomponent fibers have atrilobal cross-section and the first polymer and the second polymer arearranged in a front-to-back configuration. The multicomponent fibershave a trilobal cross section and the first polymer and the secondpolymer are arranged in a left-to-right configuration. Themulticomponent fibers have a delta cross-section. In some cases, themulticomponent fibers exhibit an overall average displacement of about−5% to about −60% over a temperature range of from −22° F. (−30° C.) to95° F. (+35° C.), e.g., about −11% to about −40% over a temperaturerange of from −22° F. (−30° C.) to 95° F. (+35° C.), e.g., about −20% toabout −40% over a temperature range of from −22° F. (−30° C.) to 95° F.(+35° C.). The multicomponent fibers include extruded fibers (e.g., apair of co-extruded fibers). The at least one raised surface is finishedin a form selected from the group consisting of: fleece, velour,shearling, pile, and loop terry. The textile fabric has a knitconstruction (e.g., a circular knit construction, a single face knitconstruction, a double face knit construction, a weft knit construction,a warp knit construction, etc.). In some cases, the textile fabric is apile fabric having woven or double needle bar Rachel warp knitconstruction.

In some examples, the second polymer is compatible with the firstpolymer. In some cases, the second material is a second polymernon-compatible with the first polymer. At least one of the first andsecond polymers is a thermoplastic polymer selected from polyester,polyurethane, polypropylene, polyethylene, and nylon. The first polymeris nylon and the second polymer is polyester. In some implementations,the multicomponent fibers also include a third polymer disposed betweenthe first and second polymers. The third polymer is more compatible withboth of the first and second polymers than the first and second polymersare with each other. The first and second polymers may includecomplementary interlocking surface features adapted to inhibitseparation of the first and second materials. In some cases. the textilefabric has a technical face formed by a stitch yarn and a technical backformed by a loop and/or pile yarn. The loop and/or pile yarn includesthe multicomponent fibers. The stitch yarn may include elastomeric yarn(e.g., spandex) for enhanced stretch and shape recovery. Thedifferential thermal elongation of the first and second polymers issubstantially reversible with low hysteresis. The adjustment toinsulation performance of the textile fabric is substantially reversiblewith relatively low hysteresis. In some implementations, the textilefabric is incorporated in a temperature responsive textile fabricgarment.

In another aspect, a textile fabric has at least one raised surfaceincorporating yarn including multicomponent fibers formed of at least apolypropylene and a polyethylene (e.g., about 50% polypropylene andabout 50% polyethylene) disposed in side-by-side relationship. Thepolypropylene and the polyethylene exhibit differential thermalelongation, which causes the multicomponent fibers to bend or curl andreversibly recover in response to changes in temperature, therebyadjusting insulation performance of the textile fabric in response toambient conditions. The yarn has a denier of about 150 to about 160. Themulticomponent fibers exhibit an overall average displacement of about−15% to about −40% (e.g., about −40%) over a temperature range of from−22° F. (−30° C.) to 95° F. (+35° C.).

Preferred implementations may include one or more of the followingadditional features. The multicomponent fibers have a trilobalcross-section and the polypropylene and the polyethylene are arranged ina front-to-back configuration.

In a further aspect, a textile fabric has at least one raised surfaceincorporating multicomponent fibers (e.g., bi-component fibers,tri-component fibers, etc.) formed of at least a first material and asecond material disposed (e.g., extruded, e.g., co-extruded) inside-by-side relationship. The first material and the second materialexhibit differential thermal elongation (e.g., expansion and/orcontraction), which causes the multicomponent fibers to bend or curl andreversibly recover in response to changes in temperature, therebyadjusting insulation performance of the textile fabric in response toambient conditions.

Preferred implementations may include one or more of the followingadditional features. The first material and the second material exhibitdifferential thermal elongation in response to changes in temperatureover a predetermined range of temperature. Preferably, the predeterminedrange of temperature in 32° F. to 120° F. More preferably thepredetermined range of temperature in 50° F. to 100° F. The raisedsurface is finished in a form selected from the group consisting of:fleece, velour, pile, shearling, and loop terry. The textile fabric hasa knit construction selected from the group consisting of: circular knitconstruction, single face knit construction, double face knitconstruction, weft knit construction, and warp knit construction. Thetextile fabric is a pile fabric having woven or double needle bar Rachelwarp knit construction. The multicomponent fibers include bi-componentand/or tri-component fibers. The first material is a first polymer, andthe second material is a second polymer compatible with the firstpolymer. The first and/or second material comprises a thermoplasticpolymer selected from the group consisting of: polyester, polyurethane,and/or nylon. The first material is a first polymer (e.g., nylon), andthe second material is a second polymer (e.g., polyester) non-compatiblewith the first polymer. The multicomponent fibers can also include athird polymer disposed between the first and second polymers. The thirdpolymer may be more compatible with both of the first and secondpolymers than the first and second polymers are with each other. Thefirst and second materials may include complementary interlockingsurface features adapted to inhibit separation of the first and secondmaterials. The fabric body has a technical face formed by a stitch yarnand a technical back formed by a loop and/or pile yarn including themulticomponent fibers. The thermal fabric can include elastomeric yarn(e.g., spandex such as Lycra®) incorporated in the stitch yarn forenhanced stretch and shape recovery. The differential thermal elongationof the first and second materials is substantially reversible with lowhysteresis. The adjustment to insulation performance of the textilefabric is substantially reversible with relatively low hysteresis.

According to another aspect, a temperature responsive textile fabricgarment includes a knit thermal fabric having a first raised surface,towards the wearer's skin, formed of one or more yarns made ofmulticomponent fibers. The multicomponent fibers include a first fibercomponent and a second fiber component arranged in a side-by-sideconfiguration. The multicomponent fibers have differing thermalproperties, which causes the multicomponent fibers to bend or curl andreversibly recover in response to changes in temperature, therebyadjusting insulative properties of the textile fabric garment. Preferredimplementations may include one or more of the following additionalfeatures. The knit thermal fabric includes a inner surface, towards thewearer's skin, having one or more regions of raised loop and/or pileyarn. The raised loop and/or pile yarn exhibits changes in bulk ofbetween about 5% to about 50% over a temperature range of between about32° F. and about 120° F. Preferably, the property of changing bulk as afunction of ambient temperature changes is reversible with relativelylow hysteresis. The multicomponent fibers exhibit changes incross-sectional area from between about 5% to about 50% over atemperature range of between about 32° F. and about 120° F. The firstand/or second fiber component may be a copolymer or a block polymer. Thefirst and second fiber components may be secured together with physicalanchoring. The first and second fiber components can includecomplementary interlocking surface features adapted to inhibitseparation of the first and second materials. The multicomponent fibersinclude bi-component and/or tri-component fibers. The first fibercomponent includes a first polymer, and the second fiber componentincludes a second polymer compatible with the first polymer. The firstfiber component includes a first polymer (e.g., polyester), and thesecond fiber component includes a second polymer (e.g., nylon)non-compatible with the first polymer. The multicomponent fibers canalso include a third polymer disposed between the first and second fibercomponents. The third polymer is compatible with both of the first andsecond polymers. The multicomponent fibers may include an additive(e.g., silicate, zeolite, titanium dioxide, etc.) physically anchoringthe first and second fiber components together. At least one of thefirst or second fiber components includes a serrated surface. Themulticomponent fibers have one or more serrated surfaces. Themulticomponent fibers have a substantially rectangular cross-sectionalshape. The first and second fiber components have a substantiallycircular cross-sectional shape. The knit thermal fabric has a secondraised surface, opposite the first raised surface, including one or moreregions of raised loop and/or pile yarn. The second raised surfaceincludes one or more yarns made of multicomponent fibers.

In yet another aspect, a method of forming a temperature sensitivetextile fabric element for use in an engineered thermal fabric garmentincludes forming a continuous web of yarn and/or fibers including one ormore multicomponent fibers. The method also includes finishing a firstsurface of the continuous web to form one or more regions of loop and/orpile yarn having a predetermined pile height and comprising the one ormore multicomponent fibers. The multicomponent fibers are formed of atleast a first material and a second material disposed in side-by-siderelationship. The first material and the second material exhibitdifferential thermal elongation, which causes the multicomponent fibersto bend or curl and reversibly recover in response to changes intemperature, thereby adjusting insulation performance of the textilefabric in response to ambient conditions.

Preferred implementations may include one or more of the followingadditional features. The method may also include finishing a secondsurface of the continuous web to form one or more other regions of loopand/or pile yarn comprising the multicomponent fibers. The step offorming the continuous web of yarn and/or fiber includes combining yarnand/or fibers by use of electronic needle and/or sinker selection. Thestep of finishing the first surface of the continuous web to form theone or more regions of loop and/or pile yarn having the predeterminedpile height includes forming loops at the technical back of the textilefabric element. The step of forming the continuous web of yarn and/orfibers includes combining yarn and/or fibers, including the one or moremulticomponent fibers, by tubular circular knitting. The step of formingthe continuous web of yarn and/or fibers includes combining yarn and/orfibers, including the one or more multicomponent fibers, by reverseplating. The step of finishing the first surface includes finishing thefirst surface to form a single face fleece. The method may also includefinishing a second surface of the continuous web to form a double facefleece. The step of forming the continuous web of yarn and/or fibersincludes combining yarn and/or fibers, including the one or moremulticomponent fibers, by plating. The step of forming the continuousweb of yarn and/or fibers includes combining yarn and/or fibers,including the one or more multicomponent fibers, by regular plating; andwherein finishing the first surface further comprises finishing thefirst surface to form a single face fleece. The step of forming acontinuous web of yarn and/or fibers comprises combining yarn and/orfibers, including the one or more multicomponent fibers, by warpknitting (e.g., double needle bar warp knitting, e.g., Raschel warpknitting). In one example, the step of forming a continuous web of yarnand/or fibers comprises combining yarn and/or fibers by Raschel warpknitting and the method includes cutting an interconnecting pile,thereby forming a single face cut pile fabric. In this case, the methodmay also include raising yarns forming a technical face of the cut pilefabric, thereby forming a double face fabric. The step of forming acontinuous web of yarn and/or fibers comprises combining yarn and/orfibers, including the one or more multicomponent fibers, by sliverknitting. The step of finishing the first surface of the continuous webto form one or more regions of loop and/or pile yarn having thepredetermined pile height includes raising the first surface. The methodmay include raising a second surface, opposite the first surface, of thecontinuous web. The method may also include cutting the loops of the oneor more regions of loop and/or pile yarn, and finishing the cut loops toa common pile height. The first material and the second material exhibitdifferential thermal elongation, e.g., expansion and/or contraction, inresponse to changes in temperature over a predetermined range oftemperature. Preferably, The predetermined range of temperature in 32°F. to 120° F., more preferably, in 50° F. and about 100° F. The methodmay also include combining the first material and the second material toform the one or more multicomponent fibers. Combining the first materialand the second material may include co-extruding the first and secondmaterials. The first and second materials are non-compatible polymers,and combing the first material and the second material may includeco-extruding the first and second materials with a third polymer suchthat the third polymer is disposed between the first and secondmaterials in the multicomponent fiber. The third polymer is compatiblewith both the first and second materials. Combining the first materialand the second material may include physically anchoring the firstmaterial to the second material. Physically anchoring the first materialto the second material may include adding an additive, such as silicate,zeolite, titanium dioxide, etc., to one or both the first and secondmaterials, wherein the additive is operable bridge between the first andsecond materials physically or chemically. The first and/or secondmaterial may be selected from the group consisting of: polyester,polyurethane, and nylon The one or more regions of loop and/or pile yarnexhibit changes in bulk from between about 5% and about 50% over atemperature range of between about 50° F. and about 100° F. The one ormore multicomponent fibers exhibit changes in cross-sectional area frombetween about 5% and about 50% over a temperature range of between about50° F. and about 100° F.

The details of one or more embodiments of the invention are set forth inthe accompanying drawings and the description below. Other features,objects, and advantages of the invention will be apparent from thedescription and drawings, and from the claims.

DESCRIPTION OF DRAWINGS

FIGS. 1A-1C are detailed views of a temperature responsive bi-componentfiber.

FIGS. 2A-2B are cross-sectional views of temperature responsive smarttextile fabric.

FIG. 3 is a perspective view of temperature responsive smart textilefabric garment.

FIGS. 3A-3C are detailed cross-sectional views of a temperatureresponsive smart textile fabric garment.

FIGS. 4A and 4B are detailed views of one embodiment of a temperatureresponsive bi-component fiber having a substantially rectangularcross-sectional shape.

FIG. 5 is a detailed view of a temperature responsive bi-component fiberhaving serrated surfaces.

FIGS. 6-9 illustrate various approaches for securing individual fibercomponents of a multicomponent fiber together.

FIG. 10 is a cross-section of a first sample yarn, sample yarn 1, a 144filament formed of round, bi-component fibers consisting ofpolypropylene and polyethylene arranged in a side-by-side configuration.

FIG. 11 shows photographs, of a multicomponent fiber undergoing athermal displacement test.

FIG. 12 is a graphical depiction of thermal displacement test resultsobtained for test fibers of sample yarn 1.

FIG. 13 is a cross-section of a second sample yarn, sample yarn 2, a 72filament yarn formed of trilobal, bi-component fibers consisting ofpolypropylene and polyethylene arranged in a front-to-backconfiguration.

FIG. 14 is a graphical depiction of thermal displacement test resultsobtained for test fibers of sample yarn 2.

FIG. 15 is a graphical depiction of thermal displacement test resultsobtained for test fibers of a third sample yarn, sample yarn 3, a 144filament yarn formed of trilobal, bi-component fibers consisting ofpolypropylene and polyethylene arranged in a front-to-backconfiguration.

FIG. 16 is a cross-section of a 72 filament yarn formed of trilobal,bi-component fibers consisting of polypropylene and polyethylenearranged in a left-to-right configuration.

FIG. 17 is a cross-section of a 72 filament yarn formed of bi-componentfibers having a rectangular shape and consisting of polypropylene andpolyethylene arranged in a side-by-side configuration.

FIG. 18 is a detailed view of a temperature responsive bi-componentfiber.

Like reference symbols in the various drawings indicate like elements.

DETAILED DESCRIPTION

FIG. 1A is a detailed view of a bi-component fiber 10. Fiber component10 includes two temperature responsive materials, i.e., first and secondfiber components A, B arranged in side-by-side relationship. The firstand second fiber components A, B exhibit differential thermalelongation, e.g., expansion and or contraction, in response to changesin temperature. As result, the fiber has a tendency to bend and/or curlin response to ambient conditions. Suitable materials for the firstand/or second fiber components A, B include polyester, polyurethane, andnylon.

For example, in one embodiment, the first fiber component A has arelatively greater coefficient of thermal expansion (i.e., a greaterpropensity to grow and/or expand in response to an increase intemperature) than the second fiber component B. When the fiber 10 isexposed to heat over a critical temperature range, the first fibercomponent A expands at a relatively greater rate than the second fibercomponent B causing the fiber to bend (see, e.g., FIG. 1B). If thedifferential elongation (e.g., expansion and/or shrinkage) exceeds acertain threshold level the fiber 10 will tend to curl (see, e.g., FIG.1C). This process is also reversible with low hysteresis; i.e., thefiber 10 will return toward its original three dimensional configurationonce the temperature returns below the critical temperature range.Suitable bi-component fibers of this type are produced by MideTechnologies Corporation of Medford, Mass.

FIG. 2A illustrates a temperature responsive textile fabric 20 includinga raised surface of bi-component fibers 10 of the kind described above.The fabric 20 includes a generally sheet-form base 22, preferably ofknit construction, having at least one raised surface 24 (e.g., pileyarn in warp knit or special circular knit) including a bi-componentfiber 10 (e.g., as a sinker loop yarn, or pile). Yarns formed of thefibers 10 can have a denier of about 90 to about 500, e.g., about 150 toabout 360. Yarns formed of the fibers 10 can have a tenacity of about0.5 grams-force per denier to about 5.0 grams-force per denier, e.g.,about 2.3 grams-force per denier. Change in thermal insulation of thetextile fabric 20 is a result of change in the bulk/thickness of pileyarn forming the raised surface when the pile yarn is made ofbi-component fibers 10 and exposed to different temperatures.

In any of the foregoing knit constructions, elastomeric yarn may beadded (e.g., spandex such as Lycra®) to, e.g., the stitch yarn. Forexample, in some cases, spandex is incorporated in the stitch yarn forenhanced stretch and shape recovery. As the ambient temperature isincreased, the fibers of the raised surface(s) begin to bend and/or curltoward the surface changing the loft and density of the fabric, and, asa result, adjust the insulation performance of the fabric 20. FIG. 2Billustrates the behavioral response of a double face temperatureresponsive textile fabric.

In one example, as shown in FIG. 3, the temperature responsive textilefabric 20 can be incorporated in a fabric garment 30. As illustrated inFIG. 3A, the raised surface 24, including the bi-component fibers 10,contacts the user's skin S providing enhanced comfort, water management,and enhanced air movement and ventilation. As the ambient temperatureincreases, the fibers of the raised surface begin to bend (FIG. 3B) andcurl (FIG. 3C) changing the three dimensional configuration of thefabric, thereby modifying the thermal insulation of the garment; i.e.,as the ambient temperature increases the fabric gets thinner (lessloft), therefore less insulation, providing enhanced overall comfort.

Preferably, the changes in three dimensional configuration occur over atemperature range of between about 32° F. and about 120° F., morepreferably, between about 50° F. and about 100° F.

A number of embodiments of the invention have been described.Nevertheless, it will be understood that various modifications may bemade without departing from the spirit and scope of the invention. Forexample, the bi-component fibers may have a variety of cross-sectionalshapes. FIG. 4A, for example, illustrates one embodiment of abi-component fiber 40 having a substantially rectangular cross-sectionwith long sides 43, 44 and short sides 45, 46. The bi-component fiber 40includes two different polymers, i.e., first and second fiber components41, 42 arranged in side-by-side relation, which exhibit differentialthermal elongation, e.g., expansion and/or contraction, in response tochanges in temperature. In this example, the first fiber component 41has a relatively greater coefficient of thermal expansion than thesecond fiber component 42. Thus, as with the bi-component fibersdescribed above (e.g., with regard to FIGS. 1A-1C), when the fiber 40 isexposed to heat over a critical temperature range, the first fibercomponent 41 expands at a relatively greater rate than the second fibercomponent 42 causing the fiber to bend (see, e.g., FIG. 4A), and, ifand/or when the differential elongation (e.g., expansion and/orcontraction (shrinkage)) exceeds a certain threshold, the fiber 40 willtend to curl (see, e.g., FIG. 4B). Due to the substantially rectangularcross-sectional shape, the bi-component fiber 40 will tend to bendrelatively easily along the long sides 43, 44 (as indicated by arrow 47in FIG. 4A), e.g., as compared to the short sides 45, 46. This processis also reversible with low hysteresis; i.e., the fiber 40 will returntoward its original three dimensional configuration once the temperaturereturns below the critical temperature range.

The bi-component fibers can have plain surfaces and/or one or moreserrated surfaces. For example, FIG. 5 illustrates a bi-component fiber50 that includes first and second fiber components 51, 52 havingserrated surfaces 53, 54. The serrated surfaces can provide a differentvisual appearance, tactile properties, toughness, and/or lightreflectance, e.g., as compared to the plain surfaces illustrated inFIGS. 1A and 4A.

In some embodiments, the bi-component fiber can include twonon-compatible polymers (i.e., fiber components) or polymers with poorcompatibility such as nylon and polyester. For example, in some casesthe bi-component fiber may include nylon and polyester fibers disposedin side-by-side relationship. Fibers formed with non-compatible polymersor polymers with poor compatibility may exhibit a tendency to split;i.e., the individual fiber components may exhibit a tendency toseparate, which can alter the effects of the bi-component response tochanges in temperature.

FIGS. 6 and 7 illustrate an approach for inhibiting separation ofindividual fiber components of a multicomponent fiber. FIG. 6illustrates the approach as applied to a tri-component fiber 60 thatincludes first and second fiber components 61, 62 having substantiallycircular cross-sections. As shown in FIG. 6, a third polymer 63 isdisposed between (e.g., co-extruded with) the first and second polymers(i.e., first and second fiber components 61, 62). The third polymer 63is used as a bridge to aid in securing the first and second polymerstogether. The third “bridge” polymer 63 can be more compatible with eachof the first and second polymers than the first and second polymer arewith each other, thereby providing a stronger bond between the first andsecond polymers and reducing the likelihood of separation.

FIG. 7 illustrates the approach described above with regard to FIG. 6,as applied to a tri-component fiber 70 that includes first and secondfiber components 71, 72 having substantially rectangular cross-sectionswith serrated surfaces 73, 74. As shown in FIG. 7 a third polymer 75 isused as a bridge to secure non-compatible polymers of first and secondfibers components 71, 72.

FIGS. 8 and 9 illustrate another approach for inhibiting separation ofindividual fiber components of a multicomponent fiber, in which theindividual fiber components are secured together by physical anchoring.This approach may be used alone or in combination with the approachdescribed above with regard to FIGS. 7 and 8. The physical anchoring canbe achieved by providing different, interlocking shapes along matingsurfaces at the interface of the fiber components. For example, as shownin FIG. 8, mating surfaces of the first and second fiber components 81,82 are provided with complementary interlocking features 83, 84 whichoperate to anchor the first and second polymers together. Alternativelyor additionally, as shown for example in FIG. 9, physical anchoring canbe achieved by adding an additive 93 (such as silicate, zeolite,titanium dioxide (TiO₂), etc.), which will physically or chemicallybridge between first and second fiber components 91, 92 of amulticomponent fiber 90, thereby anchoring the fiber components 91, 92together.

In some embodiments, a temperature responsive textile fabric, such asthe temperature responsive smart textile fabric of FIGS. 2A and 2B,suitable for use in a fabric garment, such as the garment describedabove with reference to FIG. 3, can incorporate yarns that includebi-component fibers consisting of propylene and polyethylene (e.g.,linear low density polyethylene (LLDPE)). Yarns formed of thebi-component fibers can have a denier of about 90 to about 500, e.g.,about 150 to about 360. Yarns formed of the bi-component fibers can havea tenacity of about 0.5 grams-force per denier to about 5.0 grams-forceper denier, e.g., about 2.3 grams-force per denier. Change in thermalinsulation of the textile fabric/fabric garment is a result of change inthe bulk/thickness of the pile yarn when the pile yarn is made ofbi-component fibers and exposed to different temperatures.

Table 1 shows a number of sample yarns that were each formed ofbi-component fibers consisting of a first polymer (PH-835 polypropylene,manufactured by Basell Canada Inc., Corunna, Ontario, sold under thetrademark Pro-fax™ PH835 described in Material Safety Data Sheet PH835of Basell, Issue Date: Mar. 28, 2000, Revision No.: New MSDS, the entiredisclosure of which is incorporated herein by reference) and a secondpolymer (linear low density polyethelene, e.g., 8335 NT-7 LLDPEavailable from The Dow Chemical Company, Midland, Mich. and described inMaterial Safety Data Sheet 22539/1001 of Dow Chemical Company, IssueDate: Sep. 18, 2008, Version: 2.2, the entire disclosure of which isincorporated herein by reference) at a 50/50 ratio.

TABLE 1 Filament Average Sample Polymer Polymer Material Cross DrawAverage Average Tenacity Yarn # A B Ratio Section Ratio DenierElongation gpd 1 PH-835 8335 50/50 144   4:1 320.3 101% 2.39 PP NT-7 RNDS/S LLDPE 2 PH-835 8335 50/50 72 TRI 3.50:1 159.7 111% 2.28 PP NT-7 F/BLLDPE 3 PH-835 8335 50/50 144 TRI  3.5:1 317.7 118% 2.24 PP NT-7 F/BLLDPE

Referring to Table 1, sample yarn 1 was a 144 filament yarn. Sample yarn1 had an average denier of 320.3, exhibited an average elongation of101%, and had an average tenacity of 2.39 grams-force per denier (gpd).As shown in FIG. 10, the filaments of sample yarn 1 have a round (RND)cross-section, in which the first and second polymers had beenco-extruded in a side-by-side (S/S) configuration.

A total of four single fiber thermal displacement tests were run on testfibers of sample yarn 1. FIG. 11 shows photographs, of a fiber undertest, from an exemplary thermal displacement test. The top two imagesare front and side views (on the left and right hand side of the page,respectively) of a fiber under test at the starting temperature of −30°C. (−22° F.). As shown in FIG. 11, at −30° C. the individual fiber is ina substantially vertical orientation. As the temperature is increased to0° C. (32° F.), the loft (i.e., the height of the fiber in the verticaldirection) decreases, as shown in the middle two images of FIG. 11. Theloft of the fiber under test continues to decrease as the temperature isincreased to +35° C. (95° F.), as shown in the bottom two images of FIG.11.

FIG. 12 is a graphical depiction of the test results obtained for thetest fibers of sample yarn 1. FIG. 12 shows the % Average Displacementas a function of Dwell Temperature for each of the four single fiberthermal displacements tests for sample yarn 1, as well as an overallcomputed average. The % Average Displacement is calculated bydetermining a % change in height (loft) H1 (see, e.g., FIG. 11) for thefront view of the fiber under test and a % change in height (loft) H2(see, e.g., FIG. 11) for a side view of the fiber under test and thentaking an average of those two values. As shown in FIG. 12, the fiber ofsample yarn 1 exhibited an overall average displacement of −15% over thetemperature range of −30° C. (−22° F.) to +35° C. (95° F.). Identicaltests were conducted for sample yarns 2 and 3.

Sample yarn 2 was a 72 filament yarn. Sample yarn 2 had an averagedenier of 159.7, exhibited an average elongation of 111%, and had anaverage tenacity of 2.28 grams-force per denier (gpd). As shown in FIG.13, the filaments of sample yarn 2 have a trilobal (TRI) cross-section,in which the first and second polymers (PH-835 PP and 8335 NT-7 LLDPE,respectively) had been co-extruded, side-by-side, in a front-to-back(F/B) configuration.

A total of four single fiber thermal displacement tests were also run ontest fibers of sample yarn 2. FIG. 14 depicts the test results obtained.FIG. 14 shows the % Average Displacement as a function of DwellTemperature for the fiber of sample yarn 2 for each of the four singlefiber thermal displacements tests, as well as an overall computedaverage. The fibers of sample yarn 2 exhibited a decrease in height withincreasing temperatures. As shown in FIG. 14, the fiber of sample yarn 2exhibited an overall average displacement of −40% over the temperaturerange of −30° C. (−22° F.) to +35° C. (95° F.).

Sample yarn 3 was a 144 filament yarn having a trilobal cross-section inwhich the first and second polymers (PH-835 PP and 8335 NT-7 LLDPE,respectively) have been co-extruded, side-by-side, in a front-to-back(F/B) configuration. Sample yarn 3 had an average denier of 317.7,exhibited an average elongation of 118%, and had an average tenacity of2.24.

A total of four single fiber thermal displacement tests were run on anindividual filament of sample yarn 3. FIG. 15 depicts the test resultsobtained. FIG. 15 shows the % Average Displacement as a function ofDwell Temperature for the fiber of sample yarn 3 for each of the foursingle fiber thermal displacements tests. The fiber of sample yarn 3also exhibited a decrease in height with increasing temperatures. Asshown in FIG. 15, the fiber of sample yarn 3 exhibited an overallaverage displacement of −12% over the temperature range of −30° C. (−22°F.) to +35° C. (95° F.).

FIG. 16 shows another embodiment of a 72 filament yarn having filamentswith a trilobal cross-section. In the individual filaments shown in FIG.16, the first and second polymers (PH-835 PP and 8335 NT-7 LLDPE,respectively) have been co-extruded side-by-side, in a left-to-right(L/R) configuration.

Other suitable polypropylenes include 360H PP, available from Braskem PPAmericas, Inc, and described in Material Safety Data Sheet CP360HHomopolymer Polypropylene published by Sunoco Chemical, Revision Date:Mar. 26, 2008, which references Material Safety Data Sheet code numberC4001 published by Sunoco Chemicals, dated Jan. 25, 2006, the entiredisclosure of both of these Material Safety Data Sheets are incorporatedherein by reference).

Other fiber cross-sections are also possible. For example, FIG. 17 showsa component yarn that include bi-component fibers(polypropylene/polyethylene) having a rectangular cross-section. Otherfibers may have a delta cross-section. In some case, for example, yarnsmay include fibers (e.g., multi-component fibers) having different,relative cross-sectional shapes. For example, some yarns may includeround fibers and tri-lobal fibers.

In some embodiments, a temperature responsive textile fabric, suitablefor use in a fabric garment, can incorporate yarns that includetri-component fibers consisting of three types of propylene (e.g.,Isotactic polypropylene (iPP), Syndiotactic polypropylene (sPP), andPolypropylene PP).

While yarns comprising fibers of various cross-sectional shapes havebeen described other shapes are possible. For example, FIG. 18illustrates an exemplary fiber having a delta cross-section, which canbe incorporated into a multifilament yarn. As shown in FIG. 18, thefiber 100 includes a first polymer 102 and a second polymer 104 extrudedin side-by-side configuration.

In some implementations, the textile fabric may be produced by anyprocedure suitable for combining yarns and/or fibers to create afinished fabric having at least one raised surface. The first and secondmaterials of the multicomponent fibers can exhibit differentialelongation in response to changes in relative humidity, or changes inlevel of liquid sweat (e.g., where the temperature responsive fabric isincorporated in a garment). The raised surface can be finished asfleece, velour, pile and/or terry loop. The temperature responsivetextile fabric can be incorporated in an insulative layer in amulti-layer garment system. Accordingly, other embodiments are withinthe scope of the following claims.

1. Textile fabric having at least one raised surface incorporating yarncomprising multicomponent fibers formed of at least a polypropylene anda polyethylene disposed in side-by-side relationship, the polypropyleneand the polyethylene exhibiting differential thermal elongation to causethe multicomponent fibers to bend or curl and reversibly recover inresponse to changes in temperature, adjusting insulation performance ofthe textile fabric in response to ambient conditions.
 2. The textilefabric of claim 1, wherein the polyethylene is linear low densitypolyethylene.
 3. A textile fabric having at least one raised surfaceincorporating yarn comprising multicomponent fibers formed of at least afirst polypropylene and a second polypropylene different from the firstpolypropylene disposed in side-by-side relationship, the firstpolypropylene and the second polypropylene exhibiting differentialthermal elongation to cause the multicomponent fibers to bend or curland reversibly recover in response to changes in temperature, adjustinginsulation performance of the textile fabric in response to ambientconditions.
 4. The textile fabric of claim 3, wherein the firstpolypropylene is an isotactic polypropylene and the second polypropyleneis a syndiotactic polypropylene.
 5. The textile fabric of claim 3,wherein the multicomponent fibers further comprise a third polypropylenedifferent from both the first polypropylene and the secondpolypropylene.
 6. The textile fabric of claim 1, wherein the yarn has adenier of about 90 and to about
 500. 7. The textile fabric of claim 6,wherein the yarn has a denier of about
 160. 8. The textile fabric ofclaim 1, wherein the yarn has a tenacity of about 0.5 grams-force perdenier to about 5.0 grams-force per denier.
 9. The textile fabric ofclaim 8, wherein the yarn has a tenacity of about 2.3 grams-force perdenier.
 10. The textile fabric of claim 1, wherein the yarn has afilament count of 36 to
 144. 11. The textile fabric of claim 10, whereinthe yarn is a 72 filament yarn.
 12. The textile fabric of claim 1,wherein the multicomponent fibers have a round cross-section and thepolypropylene and the polyethylene are arranged in a side-by-sideconfiguration.
 13. The textile fabric of claim 1, wherein themulticomponent fibers have a rectangular cross-section and thepolypropylene and the polyethylene are arranged in a side-by-sideconfiguration.
 14. The textile fabric of claim 1, wherein themulticomponent fibers have a trilobal cross-section.
 15. The textilefabric of claim 14, the multicomponent fibers have a trilobalcross-section and the polypropylene and the polyethylene are arranged ina front-to-back configuration.
 16. The textile fabric of claim 14,wherein the multicomponent fibers have a trilobal cross section and thepolypropylene and the polyethylene are arranged in a left-to-rightconfiguration.
 17. The textile fabric of claim 1, wherein themulticomponent fibers have a delta cross-section.
 18. The textile fabricof claim 1, wherein the multicomponent fibers exhibit an overall averagedisplacement of about −5% to about −60% over a temperature range of from−22° F. (−30° C.) to 95° F. (+35° C.).
 19. The textile fabric of claim18, wherein the multicomponent fibers exhibit an overall averagedisplacement of about −20% to about −40% over a temperature range offrom −22° F. (−30° C.) to 95° F. (+35° C.).
 20. Textile fabric having atleast one raised surface incorporating yarn comprising multicomponentfibers formed of at least a polypropylene and a polyethylene disposed inside-by-side relationship, the polypropylene and the polyethyleneexhibiting differential thermal elongation to cause the multicomponentfibers to bend or curl and reversibly recover in response to changes intemperature, adjusting insulation performance of the textile fabric inresponse to ambient conditions, wherein the yarn has a denier of about150 to about 160, and wherein the multicomponent fibers exhibit anoverall average displacement of about −5% to about −60% over atemperature range of from −22° F. (−30° C.) to 95° F. (+35° C.).
 21. Thetextile fabric of claim 20, wherein the multicomponent fibers exhibit anoverall average displacement of −20% to about −40% over a temperaturerange of from −22° F. (−30° C.) to 95° F. (+35° C.).
 22. The textilefabric of claim 20, wherein the multicomponent fibers have a trilobalcross-section and the polypropylene and the polyethylene are arranged ina front-to-back configuration.
 23. The textile fabric of claim 20,wherein the multicomponent fibers consist of about 50% polypropylene andabout 50% polyethylene.
 24. A temperature responsive textile fabricgarment, comprising the textile fabric of claim 1 or claim 20.